This invention concerns "buckle chute" sheet folders in which a sheet of paper is driven against a stop with continued driving causing buckling of the sheet, the buckled paper drawn between a pair of mating nip rollers to fold the sheet across the width of the nip rollers. Such buckle chute folding machines are very well known in the art.
Reference is made to the present inventors' prior U.S. Pat. No. 4,842,574 issued on Jun. 27, 1989, for a "Buckle Chute Folder Having A Sheet Squaring Feature". Such machines are often adapted to varying paper sizes and allow differing fold patterns by adjustment of various machine elements. Such adjustments include adjusting the location of a stop, so as to vary the location whereat the buckle and fold on the sheet occurs.
In some folding machines, more than one fold is formed on a single sheet of paper by means of a second stage of buckling and folding, in which, after an initial folding stage, the folded paper is driven against a fixed stop and drawn into a second pair of nip rollers to cause the sheet to undergo a second folding step. By means of a movable deflector the machine can be adapted to selectively control the operation of the machine to either cause the sheet to pass into the second stage folding or to bypass the same.
Such adjustable stop and deflector elements are shown in the forementioned U.S. Pat. No. 4,842,574. See also U.S. Pat. Nos. 4,585,219; 5,076,556; 3,150,871; and 3,178,171.
For light duty machines intended for office use, it is important that the adjustment procedures for adapting the machine to various fold patterns be simple. At the same time, proper functioning of these machines also requires accurate squareness, alignment and location of the various elements, particularly the stops.
In prior U.S. Pat. No. 4,842,574 there is described a sheet squaring feature in which there is a controlled release of the paper sheet from the drive rollers intermittently to enable squaring of the sheet against the folder such that the folding occurs squarely across the width of the sheet to be folded.
A difficulty in providing adjustability has been in achieving the necessary accuracy in alignment of these elements after adjustments are made without requiring undue effort and skill in carrying out the adjustments. Such adjustability in the past has been achieved by means of a number of separately set elements, complicating the adjustment process.
It would also be advantageous if such folding machines could be provided with automatic sheet feeders and adapted to utilize cassette paper holder trays as are commonly used with modern copy machines. Again, the adaption of such automatic feeders for low cost machines is difficult due to the need for achieving very reliable operation of the machine without the need for painstaking adjustment or maintenance by skilled operating personnel.
Such machines also must be relatively low in cost and yet provide the highly reliable operation with minimal attention necessary for such application.
Another problem associated with sheet folders is the need to avoid misfeeding, double feeding, or reentry of the folded sheets into the roller sets comprising the drive and nip rollers.
It is also important to provide reliable collection and stacking of the folded sheets, particularly for automatic feed operation.
Accordingly, an object of the present invention is to provide a buckle chute folder intended for office use which is relatively simple and reliable in operation without requiring delicate or fine adjustments to be made by the operating personnel.
It is another object of the present invention to provide such buckle chute folding machine in which a single knob controls both a stop location and a deflector position in order to provide a number of operating modes which may be selected with manipulation of the knob.
It is yet another object to provide such folding machine in which the alignment and location of the stop element is accurately and reliably set such as to provide accurate and reliable operation of the machine in each of a number of folding modes.
It is still another of the present invention to provide an cassette sheet holder tray and automatic sheet feed mechanism which operates in a highly reliable manner avoiding malfunctions, to provide the convenience of automatic operation without causing unreliable operation of the machine.